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How do poisons affect the neurotransmitter acetylcholine and cause death?

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  • 1 decade ago
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    Nerve gases like sarin block acetylcholine esterase, the enzyme that breaks ACh down into choline and acetate. This extends the time that the postsynaptic receptors are exposed to ACh. At the neuromuscular junction, this causes a persistent depolarization in the muscle that prevents sodium channels from recovering from inactivation. Thus, the muscle cannot fire any more action potentials and will not contract. If it affects your diaphragm muscle, that's fatal pretty quickly.

    Sarin's action is irreversible, so it is truly a poison. But physicians may administer similar drugs (physostigmine is one) that do the same thing but are reversible. However, an overdose of these will have the same effect.

    Muscle relaxants are also drugs that affect the neuromuscular junction. They can be used safely by anesthesiologists, but would be fatal if administered to a person who was not breathing with the help of a ventilator. There are 2 forms of these drugs 1) depolarizing (succinylcholine) which binds to the postsynaptic ACh receptor and causes a persistent depolarization of the muscle. 2) nondepolarizing (curare) which binds to the postsynaptic ACh receptor and prevents ACh from binding. The channels do not open and, again, there is paralysis. There is an irreversible form of this as well. alpha-bungarotoxin, found in snake venom, will bind to the receptors and prevent channel opening.

    Some forms of snail toxins (conotoxins) will do the same.

    Its a scary world out there ....

  • Anonymous
    1 decade ago

    Do you know that if you were planning to kill somebody and get away with it , you just blew it .

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